1. Technical Field
The present invention relates to an image capturing apparatus and a focusing control method.
2. Related Art
In recent years, as the resolution of the solid-state image capturing elements, such as the CCD (Charge Coupled Device) image sensor or the CMOS (Complementary Metal Oxide Semiconductor) image sensor is becoming more and more enhanced, demand for an information equipment having photographing function, such as, for example, a digital still camera, a digital video camera, a mobile phone such as a smart phone, or a PDA (Personal Digital Assistant, portable information terminal), is rapidly increasing. In the meantime, the information equipment having image capturing function described above is referred to as an image capturing apparatus.
In the image capturing apparatus, a contrast AF (Auto Focus, automatic focusing) method or a phase difference AF method (e.g., see Patent Literature 3 (WO2013-047160)) is adopted as a focusing control method which adjusts focus to a main subject. Each of the contrast AF method and the phase difference AF method has advantages and thus, an image capturing apparatus in which both of the contrast AF method and the phase difference AF method are equipped has been also proposed (e.g., see Patent Literature 1 (JP-A-2010-139942) and Patent Literature 2 (JP-A-2010-204294)).
It has been known that the phase difference AF method lacks credibility when a high frequency component is included in an image of a subject. Accordingly, whether a periodic pattern is present in the image of the subject is determined from a frequency analysis of normal pixels, and a focusing control is performed using a contrast AF method when the periodic pattern is present in the image of the subject in Patent Literature 2.
When the credibility of the phase difference AF method is determined using detection signals of the normal pixels as disclosed in Patent Literature 2, a time is needed for the determination and thus, a time required to adjust the focus to the main subject becomes longer.